Previously we have detected an NPY-like material, which is more hydrophilic than NPY, in the bovine adrenal gland. This NPY-like material has now been characterized to be identical to NPY(1-30). In this study, the distribution of NPY (1-30) in bovine adrenal glands was examined by radioimmunoassay. NPY (1-30) immunoreactivity was found in both cortex and medulla. In the adrenal medulla, the highest concentration was detected in chromaffin granules indicating that NPY(1-30) may be secreted. NPY (1-30) was also detected in the bovine brain. Whether this peptide represents a metabolite or an active form of an NPY-related peptide remains to be established. The proposed course of this study is to explore the biological activity of NPY (1-30).